The present invention relates to an overvoltage arrester having a gas spark gap presenting an arc discharge region and provided with a spacer consisting of an insulating material for the electrodes and with a chamber adjoining the arc discharge region, the walls of this chamber being constituted by the two electrodes and the spacer.
Such arresters are conventional, as disclosed, for example, in the article "Protection of Electronic and Telecommunications Systems with Spark Gap" in Nachrichten-Elektronik [Communication Electronics]4: 127-130 (1979). The arresters described in this article present in most cases two- or three-electrode spark gaps with a hermetically sealed gas filling. Such spark gaps are suitable for protecting telecommunication cables or receiving antennas against lightning flashovers, but are adequate only for operative insulation and do not meet the increased requirements for protective insulation.
FRG DOS 2,641,858 likewise discloses an overvoltage protector for telecommunication lines consisting of a structure forming a spark gap between two carbon electrodes, an area being provided around the zone of arc discharge serving as an outlet for particles escaping from the electrodes into the gap. This spark gap, too, suffices merely for operative insulation and moreover exhibits an only very limited lifetime.